Cribellate Orb Weaver

As I was walking through the woods near my home in Florence, AL- I inadvertently wandered into a spider web that had been built parallel with the ground- rather than perpendicular as most spider webs are.  A small brownish spider (about 5mm in length) with 2 very long front legs was resting beneath the spiderweb and was hanging upside down- very much like the Mabel Orchard spider.

I had found a Cribellate Orb Weaver (also known as the Featherlegged Orb Weaver)- probably a Uloborus glomosos.

This is a very harmless looking spider, isn't it?  However, its scientific name of Uloborus is from the Greek word ouloboros which translates to "with deadly bite."  Gulp.  And I had touched it.  (source)

Fortunately, in a scientific naming  irony- this spider doesn't have any venom- which is very UNLIKE most other spiders.  The cribellate spiders are unique in that aspect.  Many species of spiders utilize venom to aid in the subduction of their prey- but NOT the Cribellate Orb Weavers.  "Deadly bite" indeed.  Hmmph.

OK, so we now know that these spiders are unable to use a venom to help in the subduing of their lively meals.  So, how do they catch their meals?  Unlike many other spiders- the cribellate spiders do not have a sticky web for helping to trap their prey.  And THAT is a great clue as to why it is known as "cribellate" and feather-legged.   Wikipedia has the following description regarding cribellum: A cribellum is a kind of comb-like device in certain spiders, used to separate fibers of silk drawn from its spinnerets into many extremely fine fibers, giving it a wooly structure. Those fibers are so small in diameter that prey insects easily become entangled in them, without any glue needed. The spiders then bite them before they can get away.

The comb-like appendages on the two front legs are visible in the accompanying photo.  That may explain why the front legs are disproportionally longer than many other spiders- they probably aid the spider in the combing of the web strands.

Nature is cool- isn't it?  The following is a review of some of the interesting facts about this spider:
  • It is unique among spiders because it doesn't possess venom glands
  • But, its scientific name is Uloborus which is Greek for "with deadly bite."
  • It has two front legs are much longer than its other legs and they are equipped with "combs" that the spider uses for combing its web to separate the strand fibers to aid in ensnaring its prey.
  • It doesn't have a sticky web like many other orb weaver spiders.
  • Its web is built parallel to the ground (rather than perpendicular like most other orb weavers)
  • It rests in its web upside down- much like the Mabel Orchard spider.

5 comments:

Eve said...

Great research Daniel...I feel like I need to take a test now! I was spured on to go back and read many of your other spider articles...like I don't have anything else to do...but they are so interesting! Note: I have seen a velvet ant here...or was it a wasp...or a spider...way to go Daniel!
After reading this post I am reminded of why I spend so little time in my woods...I need to make a trail for sure.
Thanks Daniel, you always make my day.

The Giraffe Head Tree said...

Kinda favors that creepazoid egg-escaping spidery thing that leaps on people's faces and turns them into alien incubabors. Only smaller.

Jimmy said...

That shot is beautifully taken..Have you added affects in that pic after it is been taken...??

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Tabol Parker said...
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Tabol Parker said...

I've seen several of these spiders around my house (along with MANY other critters lol) and I find them facinating. I have several pictures of them (and my other ‘discoveries’)...including one laying [more] eggs; she had 2 eggs sacs already in her web: one of the sacs had hatched and little spiderlings were all over the place!